Those with Greddy Probfec B and trans brake

Scott Atk

Senior Member
May 25, 2001
I finally got my shifter mounted microswitch hooked up and I gotta say, it works pretty slick. For those wondering what I'm talking about, the Greddy Profec B spec 2 is an electronic boost controller with a lo and hi boost setting, you can hook up an external switch to change between the two. I hooked up a microswitch so when I stage it's on the low setting (probably around 18 psi) Then when I launch (push the shifter out of first gear) it switches to the hi setting (around 28 psi) Works like a champ. I'm going to the track tonight so I'll report back.
Here's a pic of the switch. As a bonus it's accessible so I can toggle between the two settings with my finger.


  • Picture 872.jpg
    Picture 872.jpg
    63.4 KB · Views: 343
My new "two step" boost controller worked pretty good last night. Would of done much better with a little track prep, but that's unheard of at the "Midnight Mayhem" events. Even so, I slightly lowered my personal best with a 9.85 @ 138.3 and a 1.45 60 ft.
so can u tell me u love the profec..i've been trying to get some info/reviews about it....
I do. There is a small learning curve with it, but once you figure it out its great. I also highly recommend Eric @ B&E customs when you're ready to buy.
in an answer to scott in another thread refered here
on the two step that i use, the innovative MSBC-1
AFIK it uses the same boost solenoids as the greedy , one for increase and one for decrease
took me a while to get it working properly due to plumbing issues, wastegate , and and controller settings that i wasnt fully aware of, but it seems to be working fine now

the msbc-1 has a stage feature (two step ) that is activated by a micro switch on the shifter which supplies 12v to a launch wire on the unit when engaged

i use the stock shifter and micro switch mounted on the lower shifter frame so at low (1st) it is engaged , I had the switch there to use the MSD dis -4 two step which is no longer in use. shifting to low also happens to mechanically engage my trans brake (stageright)

the msbc-1 allows you to select your boost level , i had to put a new spring in my HKS gate to allow this to be a reasonable level , i had a 22 psi spring and replaced that with a 5 psi , with foot to the floor i can now launch as low as 4 psi and the boost wil not budge and rpm holds dead steady .
once I shift off low the controller advances to the next stage and boost will rise to the next preset boost level (stage 1) , there are 6 stages either advanced through during a run by a switch (momentary switch at clutch pedal or on the shifter for auto) . with the new controller it can also be set to advance by timers for each stage and this I'm beginning to play with and like it.
timers start once you launch and are adjustable in 100th sec increments up to 4.99 seconds per stage , so you can program stages to lower boost at big end of track , you can also vary the rate of the boost from 40psi per second (quickest rise) to 2 psi persecond(slowest rise) in 9 steps inbetween . you can also chose a split ramp , 70% at quickest rise rate then the remaining 30% of your target boost slowed from 40psi down to 2psi per/second rise , this would help if traction were an issue from quick spool or under tired cars or poor track conditions.
before going to the lanes i set my launch boost , set 1st stage boost and how long i want to be in it (can run a little more boost in 1st 2nd gear to get car out fast ) , then set second stage of boost for remainder of second gear since stages can only be 4.99 seconds long , then knowing when third is supposed to be shifted i can pull some boost back for the third stage and set it to still be on at 11 seconds into run (should be done with 1/4 by then), i set last stage of boost to a much lower setting so even ifi held throttle past the line the controller would drop the boost and slow car ,
in normal mode the controller begins to control boost once above 3 psi and then besides controlling boost it becomes a digital boost gauge
it also has another mode to engage the controller immediately upon activating another switch so you have control before 3psi , , i have yet to try it because but cant see its use unless you arent leaving using the two step